Dyestuffs of the dibenzanthrone series



Patented Dec. 22, 1931 nniran stares PATENT FQ -I MAX ALBERT KUNZ, or MANNHEIM, KARL KoEBnaLE; or UnwIosHArnN-om seiner-nan, Ann a Barron, or MANNHEIM, enniuanr, ASSIG-NORS '10 enn- ERAL ANILiNE worms rim, on NEW YORK, 1v. "2., A CORPORATION or DELAWARE DYESTUFFS OF THE BIBENZANTHEONE SERIES No Drawing. Application filerl July 24, 1929,-Seria1 No. 380,750, and in Germany August 7, 1928.

The present invention relates to the production of vat dyestuffs from nitro dibenzanthrones.

We have found that valuable dyestulfs of the 'dibenzanthrone or iso-dibenzanthrone series, which for the most part dye grey shades, are obtained by heating nitro dibenzanthrones which term is meant to comprise nitro derivatives of dibenzanthrone, iso-dibenzanthrone and derivatives thereof, alone or in an organic diluting medium to temperature above 100 C. which, however, should not be so high as to destroy the dyestuffs, preferably between about 150 and 250 centigrade. ganic diluting media comprise, for example, nitrobenzene, nitrotoluol, naphthalene, nitro naphthalene and the like. Small amounts of catalytic substances, such as metals andnon-allraline compounds may be added to the reaction mixture.

The dyestuffs obtained in accordance with the process of the present invention generally speaking dissolve in concentrated sulphuric acic. give violet red or green colorations and dye cotton grey shades of an excellent fastness from a vat which is usually blue. p

The following examples will further illustrate how the said invention may be carried out in practice, but the invention is not restricted to these examples. The parts are by weight.

EwamgeZe Z Bz. 2-nitro diben zanthrone (prepared by the nitration of pure dibenzanthrone in 11 The before-mentioned or-.

throne, a reaction product which dyes reddish grey shades is obtained.

Emample 2 5 parts of nitro dibenzanthrone (prepared tion while hot, extracted with 250 parts of trichlor benzene and treated with steam. The reaction product Which-is obtained in excellent yield dissolves in concentrated sul phuric acid to give a red violent coloration and dyes cotton Very fast grey to black shades from a blue vat.

Ewample 3 A suspension of parts of nitro dibenzanthrone obtained according to Example 2 of the United States Patent No. 7 96,893 in 1000 parts of nitrobenzene is boiled until a sample gives pure blue grey dyeings. Then the product is filtered oil by suction, or the nitroenzene distilled ofi', if desired, under reduced pressure or in steam. The dyestufi which is a blue black powder, dissolves in concentrated sulphuric acid to give a violet coloration and dyes cotton blue grey to blue black shades of excellent fastness from a reddish blue vat. 7

What we claim is 1. A process of producing vat dyestufls of the dibenzanthrone series, which comprises heating a nitro dibenzanthrone in the absence of any condensing agent to above 100 centigrade, but not so high as todestroy the dyestufl'.

2. A process of producing vat dyestuffs of the dibenzanthrone series, which comprises heating a nitro dibenzanthrone in the absence of any condensing agent to between about 150 and 250 centigrade.

3. A process of producing vat dyestuffs of the dibenzanthrone series, which comprises heating a nitro dibenzanthrone in the absence ofany condensing agent to above 100 centigrade in an inert aromatic diluent of high boiling point.

4. As a new articleof manufacturethe vat dyestufl, which forms a dark blue powder, dissolving in concentrated sulphuric acid to give aviolent red coloration, dyes cotton Very ast neutral grey shades from a blue vat and which is obtainable by sintering pure B2 2-nitr0 dibenzanthrone.

In testimony whereof We have hereunto set our hands.

' MAX ALBERT *KUN Z.

KARL KOEBERLE. WALTER 'BRUCK. 

